Powering the ABC multidrug exporter LmrA: How nucleotides embrace the ion-motive force.
Powering the ABC multidrug exporter LmrA: How nucleotides embrace the ion-motive force.
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DOI：
10.1126/sciadv.aas9365
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发表时间：
2018-09
期刊：
影响因子：
13.6
通讯作者：
van Veen HW
中科院分区：
文献类型：
--
作者：
Agboh K;Lau CHF;Khoo YSK;Singh H;Raturi S;Nair AV;Howard J;Chiapello M;Feret R;Deery MJ;Murakami S;van Veen HW
研究人员研究了不同形式的代谢能量如何通过ATP结合盒转运蛋白与药物挤出偶联。LmrA是一种细菌ATP结合盒（ABC）多药输出蛋白，它利用代谢能转运离子、细胞毒性药物和脂质。使用Port-a-Patch中的电压钳位来监测与通过单LmrA转运蛋白和转运蛋白集合转运单价阳离子HEPES+相关的电流。在这些实验中，一个质子和一个氯离子与每个HEPES+离子一起流出内室，而两个钠离子被输送到该室中。因此，钠动力（内部负和低）可以在生理条件下驱动细胞中的这种产电离子交换机制。同样的机制也与单价阳离子乙锭（一种典型的多药物转运蛋白底物）的外排有关。在Mg-ATP（5′-三磷酸腺苷）存在下的研究表明，离子偶联HEPES+转运与ATP结合的LmrA相关，而离子偶联乙锭转运需要ATP结合和水解。HEPES+在水基环境中是高度可溶的，而乙锭具有强烈的偏好，停留在斥水质膜中。我们得出结论，ABC转运蛋白LmrA的机制是从根本上相关的离子反向转运蛋白，使用额外的步骤（ATP结合和水解），以检索和运输膜可溶性底物的磷脂双层。
Researchers study how different forms of metabolic energy are coupled to drug extrusion by an ATP-binding cassette transporter. LmrA is a bacterial ATP-binding cassette (ABC) multidrug exporter that uses metabolic energy to transport ions, cytotoxic drugs, and lipids. Voltage clamping in a Port-a-Patch was used to monitor electrical currents associated with the transport of monovalent cationic HEPES+ by single-LmrA transporters and ensembles of transporters. In these experiments, one proton and one chloride ion are effluxed together with each HEPES+ ion out of the inner compartment, whereas two sodium ions are transported into this compartment. Consequently, the sodium-motive force (interior negative and low) can drive this electrogenic ion exchange mechanism in cells under physiological conditions. The same mechanism is also relevant for the efflux of monovalent cationic ethidium, a typical multidrug transporter substrate. Studies in the presence of Mg-ATP (adenosine 5′-triphosphate) show that ion-coupled HEPES+ transport is associated with ATP-bound LmrA, whereas ion-coupled ethidium transport requires ATP binding and hydrolysis. HEPES+ is highly soluble in a water-based environment, whereas ethidium has a strong preference for residence in the water-repelling plasma membrane. We conclude that the mechanism of the ABC transporter LmrA is fundamentally related to that of an ion antiporter that uses extra steps (ATP binding and hydrolysis) to retrieve and transport membrane-soluble substrates from the phospholipid bilayer.
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DOI：
10.1126/science.1246489
发表时间：
2014-03-07
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Lee JY;Yang JG;Zhitnitsky D;Lewinson O;Rees DC
通讯作者：
Rees DC
影响因子：
15
作者：
Hellmich, Ute A.;Lyubenova, Sevdalina;Glaubitz, Clemens
通讯作者：
Glaubitz, Clemens
影响因子：
7
作者：
Ishihama, Y;Oda, Y;Mann, M
通讯作者：
Mann, M
影响因子：
13.8
作者：
HIGGINS, CF;GOTTESMAN, MM
通讯作者：
GOTTESMAN, MM
影响因子：
4.8
作者：
Reuter, G;Janvilisri, T;van Veen, HW
通讯作者：
van Veen, HW